DE-OS No. 32 30 615 suggests a fiber optic sensor consisting of an elastic fiber optic waveguide with one fixed end, the other end capable of deflection when mechanical forces act thereon. The light emerging from this waveguide is directed onto the face or faces of one or more additional fiber optic waveguides. These waveguides are in turn coupled to a photo sensor. Depending upon the direction of deflection of the first waveguide, the quantity of light received by the additional waveguides varies. The received light is then converted into electrical signals. This sensor is difficult to adjust as the free end of the first waveguide must be moved perpendicularly to the faces of the additional waveguides. Consequently, slight rotation of the sensor or one-sided heat stress can lead to improper displacement of the first fiber optic waveguide.